[3.11] gh-103025: fix a ctypes doc typo (GH-103026) (#103029)

* gh-103025: fix two ctypes doc issues  (GH-103026)
(cherry picked from commit 0708437)

Co-authored-by: Peter Jiping Xie <[email protected]>

Author: miss-islington

Doc/library/ctypes.rst

@@ -374,8 +374,8 @@ that they can be converted to the required C data type::
 
 .. _ctypes-calling-variadic-functions:
 
-Calling varadic functions
-^^^^^^^^^^^^^^^^^^^^^^^^^
+Calling variadic functions
+^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 On a lot of platforms calling variadic functions through ctypes is exactly the same
 as calling functions with a fixed number of parameters. On some platforms, and in